[Illustration: Figure 4.--HOW DEERE PROBABLY CUT AND BENT THE FLAT PLATE of his 1838 plow to form the moldboard and landside. Because of the shape of the moldboard it became known as the diamond plow.] [Illustration: Figure 5.--MOLDBOARD OF 1847 JOHN DEERE PLOW, showing how the diamond shape of the original design has been slightly modified. (_Deere & Company photo 57192-D_.)] In a small, new, pioneering community it seems unlikely that the local sawmill would have been equipped with the newer circular saw rather than the familiar up and down saw which remained in use throughout the 19th century and, in places, well into the 20th century. The up and down saw was a broad strip of iron or steel with large teeth in one edge. Driven by water power it slowly cut large logs into boards. It is doubtful that the circular saws of that period were large enough for this kind of mill work. The second argument is the shape of the moldboard itself. The photograph of the 1838 plow in figure 7 shows that the shape of the moldboard is unconventional. It is essentially a parallelogram curved to present a concave surface to the furrow slice and thus to make a simple, small but workable plow. A parallelogram or diamond would be an easy shape to cut out of a mill saw with the teeth removed. The moldboard on the 1838 plow is from .228 to .238 inches thick and its width is 12 inches. These dimensions approximate those given in an 1897 Disston catalog[15] which describes mulay saws, a type of mill saw, from 10 to 12 inches wide and from 4 to 9 gauge. Gauge number 4 is the thickest and is .238 inches. Examination of the 1838 plow suggests that Deere cut the moldboard and landside as one piece, which was then heated and bent to the desired form. The pattern of this piece is shown in figure 4. Some additional metal appears to be forged into the sharp bend at the junction of the moldboard and the landside apparently to strengthen this part, which may have begun to open during the bending. If, however, Deere had used a large circular saw with plenty of room for cutting out a moldboard of the usual shape and size, it seems likely that he would have made a plow of more conventional appearance. In any event his moldboard of one jointless piece of polished metal would scour better than one of wood covered with strips of steel since the nailheads and the joints between the strips would provide places for the earth to stick. [Illustration: Figure 6.--THE SHAPE OF THE MOLDBOARD continued to evolve, as illustrated by this 1855 John Deere plow. (_Deere & Company photo 57192-A_.)]